1. Field of the Invention
The present invention relates in general to door lock devices for motor vehicles, and more particularly, to power door lock devices of a type which, when the door is closed to a half-latch position, forces the door move to a full-latch and full-closed position by electric power.
2. Description of the Prior Art
In order to clarify the task of the present invention, one conventional power door lock device of the above-mentioned type will be described, which is disclosed in, for example, Japanese Patent Second Provisional Publication 62-28271.
The door lock device of the publication comprises generally a lock proper which is mounted to a door and a striker which is secured to a vehicle body.
The door lock proper comprises a latch plate which is pivotal to assume an open position, a half-latch position and a full-latch position, a half-latch detecting switch which detects the half-latch position of the latch plate, a crank arm which is pivotally driven by an electric motor, and a close lever which is linked to the crank arm and linearly movable between inoperative and operative positions. The latch plate and the close lever are disposed on a common shaft to permit relative rotation therebetween. The open position of the latch plate is a position wherein the latch plate completely releases the striker, the half-latch position of the same is a position wherein the latch plate halfly or incompletely catches or latches the striker and the full-latch position of the same is a position wherein the latch plate completely catches or latches the striker. The inoperative position of the close lever is a position wherein the pivotal movement of the latch plate is not blocked by the close lever. When the close lever is moved from the inoperative position to the operative position, the close lever forces the latch plate to pivot from the half-latch position to the full-latch position. When the door is kept opened, the latch plate assumes the open position. When the door is pivoted to a position near a closed position, the latch plate receives the striker, and then when the door closing movement is further advanced with a certain but not strong force, the latch plate is turned by the striker from the open position to the half-latch position having the close lever left in the inoperative position. Upon this, the half-latch detecting switch detects the half-latch condition of the latch plate and energizes the electric motor to drive through the crank arm the close lever from the inoperative position to the operative position. With this, the latch plate is forced to turn from the half-latch position to the full-latch position moving the door from the incompletely closed position to a fully closed position.
However, due to its inherent construction, the above-mentioned power door lock device has the following drawback.
That is, in the door lock device, when, during the closing movement of the door, the latch plate is turned by the striker from the open position to the half-latch position, the close lever is left in the inoperative position. However, leaving the close lever at such inoperative position produces between the latch plate and the close lever a certain clearance of a size corresponding to the moved distance of the latch plate between the open position and the full-latch position. This means that before making an actual pivoting of the latch plate from the half-latch position to the full-latch position, the close lever is compelled to make a useless traveling by a distance corresponding to the certain clearance between the close lever and the latch plate. Thus, the action of the latch plate is delayed and thus quick movement of the door from the half-latch position to the full-latch full-closed position is not achieved.